While summer is normally the time to kick back and enjoy the literal fruits of your labor, there may still be a few gardening tasks lurking—such as that overgrown patch of past-bloom irises that need to be divided. Now is the right time.
Maybe they are too crowded, maybe they aren’t blooming as much as before, or maybe it’s been three to five years since they were last divided—all are good reasons to divide your irises. While there are hundreds of varieties of irises, these instructions apply to one of the most common varieties: the tall bearded iris.
Photography by Joy Yagid, unless otherwise noted.
Step 1: Dig up the irises.
Step 2: Find the healthy rhizomes.
Step 3: Keep a fan of leaves with each division.
Step 4: Divide the rhizomes.
Step 5: Trim the leaves.
Step 6: Replant the divided rhizomes.
Step 7: Be patient.
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Frequently asked questions
Why should I divide tall bearded irises?
Dividing tall bearded irises helps rejuvenate the plants, promotes better flowering, and prevents overcrowding.
When is the best time to divide tall bearded irises?
The best time to divide tall bearded irises is in late summer or early fall, after they have finished blooming.
How often should I divide tall bearded irises?
Tall bearded irises should be divided every 3 to 4 years to maintain their health and vigor.
How do I prepare the irises for division?
Start by cutting the foliage down to a height of about 6 inches. Then, carefully lift the clump of irises out of the ground using a garden fork or spade.
How do I divide the iris rhizomes?
Gently separate the rhizomes by hand or use a clean, sharp knife to cut them into smaller sections. Ensure that each section has at least one fan of leaves and healthy roots.
What should I do with the divided iris rhizomes?
Trim the leaves to about half their original length and remove any damaged or diseased parts. Allow the rhizomes to dry for a few hours before replanting or storing.
Where should I replant the divided irises?
Choose a sunny spot with well-draining soil for replanting the divided irises. Space them about 12 to 18 inches apart to allow for adequate growth.
How should I care for the newly divided irises?
Water the newly divided irises thoroughly after replanting. Provide regular watering during the first growing season and apply a balanced fertilizer in early spring.
What should I do with the excess divided iris rhizomes?
If you have more divisions than you need, consider sharing them with gardening friends or donating them to a local plant sale. Alternatively, you can store them in a cool, dry place for future use.
How long does it take for divided tall bearded irises to bloom again?
After division, tall bearded irises may take 1 to 2 years to fully establish and bloom again. Be patient and continue to provide proper care during this period.